Any old VCR has a programmable timer that connects to motors for recording TV shows. This is analogous to feeding a cat, and following this principle, you can convert a VCR into a weekend pet feeder. You set the VCR’s timer, and when feeding time comes, the motor that would ordinarily spin the video head operates a food delivery mechanism instead. You can even program different size portions for different days, for times when you plan on returning midday. Like some vending machines, the feeder uses an auger mechanism, a helical shaft, to propel food from a hopper into the pet’s bowl. You can use the same basic mechanism to drop food into a fish tank.
VCR Cat Feeder
Use an old VCR to automatically feed your pet on schedule.
- VCR (1) Test the VCR first to make sure its timer and tape transport mechanisms still function, even if it doesn't produce a watchable picture. The VCR should activate its mechanism at the set time, run the tape for the set period, then stop. If you have a choice of VCRs, go for one that you can program entirely from the front panel — this project gets cumbersome if you need to program the VCR with a remote control or via on-screen menus.
- Screws (1) plus nuts and bolts
- Hook-up wire (1) optional, depending on what you find inside your VCR
- Glue, strong (1)
- Meat grinder (1) Some kind of auger system is needed. I used an old meat grinder with a helical shaft, with the cutting blades removed. This propels the food from a container into the bowl. Make sure it works with the type of pet food you want to dispense. When choosing your auger, bear in mind that your hungry pet might try to eat, paw, or lick the system while it's in motion, and, if so, you don't want it to cause any injuries.
- Container (1) The container will connect with the auger system. I fashioned a sort of metal hopper head out of the magnetic shielding from an oscilloscope tube. As with the auger, you'll need to make sure this is pet-safe — and also pet-proof. The system won't help if your cat can jump into the hopper or knock it over. I covered mine with a plastic lid, to keep the cat out.
- Metal card frame (1) Something that can hold the assembly of auger, gearbox, and video head motor all together.
- Electrical Tape (1)
- Videocassette (1) One you don't mind sacrificing. Make sure the recording-enable tab is unbroken.
- Gearbox, A small gearbox or pulley system with a turn ratio of about 600:1. (1) This will reduce the standard 1800 RPM counterclockwise rotation of a video head motor into rotation with the right speed and torque to drive the auger. I used a gearbox from a defunct cam sequencer, but you can also get these from hobby retailers. Some good ones are made by Tamiya. The 'fast side' of the box must be able to couple to a shaft of approximately 1/2cm in diameter. Also, make sure that the 'slow side' of the gearbox can connect solidly to your auger and rotate it in the correct direction. The 'fast side' will be going counterclockwise.
- Multiway electrical connector (1) You might need this and the hook-up wire depending on what you find inside your VCR and how you arrange things.
- Ability to improvise
- Hot glue gun
- Soldering equipment